Actions may take different forms, for example a hand shaking can be gently or vigorous, a caress can be delicate or rushed. These forms of social communication which characterize how actions are performed, have been named vitality forms by Daniel Stern. Vitality forms play a crucial role in interpersonal relations. The expression of vitality forms allows the agent to communicate his own mood/attitude, while the perception of vitality forms allows the receiver to understand the mood/attitude of others.